Ball joint apparatus and a manufacturing method therefor

Abstract

A ball joint apparatus comprises a socket formed of a thermoplastic synthetic resin, a stud ball having a spherical head rotatably fitted in the socket so as to mate with a concave spherical surface thereof, and a housing containing the socket. The housing includes a cylindrical socket receiving portion, formed by plastically processing a metal sheet and a bottom wall portion. Through holes are bored through the bottom wall portion. Projections are provided on the base of the socket, corresponding in position to the through holes. The socket is fixed to the housing by inserting the projections into the through holes, softening each end portion of the projections, which projects outside the through holes, by heating or the like and transforming the end portions into a flat shape.

What is claimed is: 
     
       1. A ball joint apparatus comprising: a stud ball having a spherical head;   a socket having a concave spherical surface for receiving the spherical head for rotation; and   a housing containing the socket;   the housing including a socket receiving portion formed of a metal material and having an inner surface with a circular profile and a bottom, a bottom wall portion at the bottom of the socket receiving portion, the bottom wall portion having a plurality of small circular through holes therein; and   the socket being formed of a thermoplastic synthetic resin and having a base and projections on the base thereof, said projections being at positions corresponding to said small circular through holes, said projections being inserted into respective ones of said through holes, and said projections having end portions projecting outside said through holes, and wherein said projecting end portions of said projections are transformed so as not to be able to slip out of said through holes.   
     
     
       2. A ball joint apparatus according to claim 1, wherein the socket receiving portion of said housing is further comprises a flange at an opening thereof. 
     
     
       3. A ball joint apparatus according to claim 1, wherein said socket is formed of a fiber-reinforced plastic obtained by reinforcing a synthetic resin with short glass fibers. 
     
     
       4. A ball joint apparatus according to claim 3, wherein said socket has a diametrical direction and comprises a plurality of socket component pieces divided in the diametrical direction thereof. 
     
     
       5. A ball joint apparatus according to claim 1, wherein a plurality of said projections are arranged so that end portions of the projections which project outside the through holes are transformed to be continuous with one another. 
     
     
       6. A ball joint apparatus comprising: a stud ball having a spherical head;   a socket having a concave spherical surface for receiving the spherical head for rotation; and   a housing containing the socket;   the housing including a socket receiving portion formed of a metal material and having an inner surface with a circular profile and a bottom, a bottom wall portion at the bottom of the socket receiving portion, the bottom wall portion having one non-circular through hole therein, and   the socket being formed of a thermoplastic synthetic resin and having a base and a projection on the base thereof, said projection being at a position corresponding to said non-circular through hole, said projection being inserted into said through hole, and said projection having an end portion projecting outside said through hole, and wherein said projecting end portion is transformed so as not to be able to slip out of said through hole.   
     
     
       7. A ball joint apparatus according to claim 6, wherein the socket receiving portion of said housing further comprises a flange at an opening thereof. 
     
     
       8. A ball joint apparatus according to claim 6, wherein said socket is formed of a fiber-reinforced plastic obtained by reinforcing a synthetic resin with short glass fibers. 
     
     
       9. A ball joint apparatus according to claim 6, wherein said socket has a diametrical direction and comprises a plurality of socket component pieces divided in the diametrical direction thereof. 
     
     
       10. A method for manufacturing a ball joint apparatus which includes a stud ball having a spherical head, a socket having a concave spherical surface for receiving the spherical head for rotation, and a housing containing the socket, the method comprising: forming the housing, including a socket receiving portion, of a metal material, the socket receiving portion having an inner surface with a circular profile and a bottom wall portion, and forming a plurality of small circular through holes in the bottom wall portion;   forming projections on the base of the socket, said projections being formed of a thermoplastic synthetic resin, and said projections having respective end portions, said projections being at positions corresponding to said small circular through holes;   fitting the spherical head of the stud ball into the socket so as to mate with the concave spherical surface thereof;   inserting the socket and said projections into the socket receiving portion of the housing and said through holes, respectively, such that said end portions of said projections project outside said through holes;   softening the end portions of said projections projecting outside said through holes; and   transforming the softened end portions of said projections so that said projections are not able to slip out of said through holes.   
     
     
       11. A method for manufacturing a ball joint apparatus according to claim 10, wherein the socket has a collar portion and the housing has a flange portion, the method further comprising: securing dust cover to said housing by clamping an edge of said dust cover between the collar portion of said socket and the flange portion of said housing as said socket is inserted into said housing.   
     
     
       12. A method for manufacturing a ball joint apparatus according to claim 10, wherein said housing is formed by one of drawing, forging, casting, and sintering. 
     
     
       13. A method for manufacturing a ball joint apparatus which includes a stud ball having a spherical head, a socket having a concave spherical surface for receiving the spherical head for rotation, and a housing containing the socket, the method comprising: forming the housing, including a socket receiving portion, of a metal material, the socket receiving portion having an inner surface with a circular profile and a bottom wall portion, and forming one non-circular through hole in the bottom wall portion;   forming of a corresponding non-circular projection on the base of the socket at a position corresponding to said non-circular through hole said non-circular projection being formed of a thermoplastic synthetic resin and having an end portion;   fitting the spherical head of the stud ball into the socket so as to mate with the concave spherical surface thereof;   inserting the socket and said projection into the socket receiving portion of the housing and said through hole, respectively, such that said end portion of said projection projects outside said through hole;   softening the end portion of said projection projecting outside said through hole; and   transforming the softened end portion of said projection so that said projection is not able to slip out of said through hole.   
     
     
       14. A method for manufacturing a ball joint apparatus according to claim 13, wherein the socket has a collar portion and the housing has a flange portion, the method further comprising: securing a dust cover to said housing by clamping an edge of said dust cover between the collar portion of said socket and the flange portion of said housing as said socket is inserted into said housing.   
     
     
       15. A method for manufacturing a ball joint apparatus according to claim 13, wherein said housing is formed by one of drawing, forging, casting, and sintering.